High-resistance electrical conductor



June 22 1926. 1,590,045

C. F. LORENZ HIGH RESISTANCE ELECTRICAL CONDUCTOR Filed March 17. 1923 FIG- 1 REDUCING MATERIAL FIQZ NON CON DUCTI NG MATERIAL NOB; CONDUCTING MATERIAL INVENTOR CHARLES F LORENZ TTORNEY Patented June 22, 1926.

- UNITED STATES PATENT OFFICE.

CHARLES FREDERICK LORENZ, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WEST- INGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-RESISTAN CE ELECTRICAL CONDUCTOR.

Application filed. March 17, 1923. Serial No. 625,777. I

This invention relates to high resistance electrical conductors and to a method of making the same.

An object of the invention is to provide a conductor of such form as to be of relatively high resistance and which will occupy a comparatively small space.

Another object of the invention is to provide a resistor which will be of a durable character and not readily subject to mechanical injury.

Another'object is to provide a resistor that will not be readily over heated.

A further object is to rovide a reliable resistor free from the in uence oftemperature changes.

Other objects and advantages will be apparent upon a reading of the following description.

In making high-resistance conductors, the resistance of which is rated in megohms, various expedients have been resorted to,- amon which are the deposit of conducting material on a given non-conducting surface in the form of a thin film or of a narrow band. Resistors made by such method may be employed with certain electrical apparatus but resistors of the above type lack the durability desirable in devices of this character.

According to the present invention, a resistor of minute cross sectional area may be produced by providing a cylinder or a tube of an oxide or chemical substance, referably a refractory oxide, and then app ying a streak or winding around the oxide of a material capable of reducing the oxide when both the reducing material and the oxide are heated, in a suitable environment, to a temperature below the melting point of either.

The heating may beaccomplished either by the passage of an electric current through the reducing material or by placing the whole in an oven or furnace; the heating being performed in a vacuum or suitable atmosphere. A streak of metal will then be formed u on the oxide owing to the action of the re ucin material.

An electricaconnection may be made with the metallic streak or thread of metal in any suitable manner and a resistor obtained for various purposes as, for instance, for use as a grid leak 1n connection with radio apparatus- A more clear understanding or my invention may be had byreference to the following description and accompanying drawings in which Fig. 1 is an elevational view of an oxido body for supporting the resistor;

Fig. 2 is a view of the body as is shown in Fig. 1 but showing a helix thereon of a either.

If desirable, the reducing material may be ainted'upon the body or it may be ap lied y abrasion in the form of a pencil mar The heating may be accomplished by passing an electrical current through the strip or by placing the body, with the strip thereon, in an oven or furnace, in which they may be heated in a suitable gas inert with respect to the oxide or in a vacuum. A streak of metal 7 of helical formation will then be formed in or about the surface of the oxide, owing to the action of the material of the positioned wire. The body may then be removed from the furnace and the wire discarded. Suitable ca s 8 and 9 of a conductive material may e fitted to the ends of the body 5 in such manner that the terminals of the thread or streak 7 will be disposed in contact with the caps. The body may then be varnished for protection from the atmosphere or it may be enclosed in a sealed tube, such as the glass tube 10 shown in Fig. 3, which may be evacuated, or may contain an inert gas.

If desired, he strip 6 may have its ends slightly enlarged to give a greater surface area of conductive material at the points of contact between the caps'or conductors 8 and 9. It may, however, be preferable to connect the ends of the wire 5 to cu s of a similar material which may fit over t e ends of the bod 6, thus, when the body is subjected to t e reducing action, the layer of metal upon the body will be connected to a relatively large cyllndrical surface at each end to facilitate connection to leads.

A resistor produced by the present method .v has considerable advantages over resistor. elehandling and were liable to the detrimental efiects'caused by mechanical abrasion which would result in portions of the resistance material being removed. Such loss of resistance material would obviously seriously affect the value of the element for the purpose for which it was intended.

I It will be appreciated that various oxides may be used for the body 6 of the present invention and that different materials may be employed for the helix. As an example, thoria may be chosen as the oxide, in which case, carbon will be a suitable material for the helix- The employment of these two materials may require heating to a temperature something approaching 1400 C. but a considerably higher temperature may be used. The advantage of a 'resistor produced by the present method consists in the durability thereof, which is evident, since the metal used for the high-resistance resistor will be firmly embedded in, and intimately associated with, the supporting body or the oxide. This fact makes it extremely durable and not readily subject to mechanical injury. 4

It will be obvious that an oxide, such as chromium or cobalt oxide, may be used as a supporting body or base. A mixture of oxides or other chemical compoundsmay be employed so that the reduction will give an alloy which has a high-resistance property.

By reason of the close association of the resistor with the mass of oxide or supporting material, the heat-transfer rate may be more rapid and the resistor will not be readily overheated. Furthermore, the reistor will be more reliable in that it will not be readily subject to temperature changes by reason of its intimate contact with the oxide support which facilitates the distribution of heat. As a device for use vin connection with radio equipment, the

resistor may be of special advantage since it may prove to be free from microphonic effects which are a. source of annoyance in resistors heretofore used.

Although the present description and drawings set forth one mode of practicing ;the' invention, it is obvious that modifications .may be made therein, for instance,

other oxides or suitable chemical com- "pounds capable of reduction may be used for the supporting-{body and other materials may be'used for helix, or the body may be of a difierent shape. It is to be understood that such modifications are considered to lie within the spirit and scope of the appended claims.

What is claimed is: p

1. A high-resistanceelement comprising a non conductive body capable of reduction having a definite portion thereof reduced to an electrical conductive material and supported by said non-conductive body.

2. A high-resistance element comprising a chemical substance capable of reduction having a definite elongated portion thereof reduced to electrical conductive material.

3. A high-resistance element comprising a non-conductive oxide having a ortion thereof reduced to electrical conduct ve material.

4. A high-resistance element comprising a body composed of a mixture of chemical substances capable of reduction and having a definite portion thereof reduced to electrical conductive material boarded by said substance. I

5. A high-resistance element comprising a mixture of non-conductive oxides having a definite portion thereof reduced to electrical conductive material surrounded by said non-conductive oxides.

6. A high-resistance element comprising a body of chemical compounds capable ofreduction and having a portion thereof of helical form reduced to provide an electrical conductor.

7. A high-resistance element comprising a body consisting of a mixture of non-conductive oxides having a portion thereof reduc'ed to an electrical conductive material.

8. A high-resistance element comprising a continuous body of electrically conductive metal reduced from a supporting body consisting of the oxide of said metal.

9. A high-resistance element comprising a body of electrically conductive material reduced from, and embedded in, the surface of a refractory oxide.

10. A high-resistance element comprising a body of a refractory oxide having a filamentary helical portion thereof reduced to provide an electrical conductor.

11. The method of forming a high-resistance conductor which consists in disposing upon a body of a chemical substance capable of reduction, a streak of material capable of reducing the said substance, heating the body and streak to effect a reducing action in the substance.

12. The. method of forming a high-resistance conductor which consists in dis osing upon a body of a non-conductive bo y capable of reduction, a filamentary material capable of reducing the body, heating the body and filament to effect a reducing action on the body.

13. The method of forming a high-resistance conductor which consists in dis sing about a body of a refractory oxide, a elical winding of a material capable of reducing said oxide, placing the body and winding thereon in an inert environment and heating the body and winding to efiect a reducing action of the oxide adjacent said winding.

14. The method of forming a hi h-resistance conductor which consists in isposing about a body of thoria, a carbon strip, placing the body in a furnace, heating to a reducing temperature and finally removing the strip.

15. The method of forming a high-resistance conductor which consists in disposing about a body of thoria, a helically disposed carbon strip, placing the body in a furnace, heating to a reducing temperature and finally removing said strip.

In testimony whereof, I have hereunto subscribed my name this 16th day of March 1923.

CHARLES FREDERICK LORENZ. 

